1. Field of the Invention
The present invention relates to a method for controlling a continuously variable transmission, to an electronic control device with which such a method can be carried out, as well as to a continuously variable transmission.
2. Description of the Related Art
Methods for controlling a continuously variable transmission are known, as are continuously variable transmissions that have a two-stage torque sensor. Such two-stage torque sensors have a mechanical input member and a mechanical output member. The mechanical input member and the mechanical output member each include a ramp system. One or several balls are arranged between the ramp systems so that a torque load imposed upon the input member is transmitted by the balls to the output member.
The output member, that is, piston surfaces, operate on a hydraulic system. The hydraulic system includes a first chamber and a second chamber that are each filled with an hydraulic medium, and that are each loaded by an effective area of the output member. The effective area that operates on the first chamber and the effective area that operates on the second chamber are connected together. Additionally, a connecting conduit that can be opened and closed is also arranged between the first chamber and the second chamber. One of the chambers can also be adjusted to be essentially depressurized or at ambient pressure, wherein the effective area loaded by that chamber does not change the pressure in that chamber independently of a load. The other of those chambers is connected to a third effective area, which influences a disk set of the continuously variable transmission, in particular either directly or through at least one interconnected component.
Depending upon the opening status of the connection passageway between the first and the second chamber a higher or a lower pressure can be produced in the chamber system. Different forces can then act on the disk set as a function of the effective area acting on the disk set and as a function of those different pressures.
The switchover between the stages of the torque sensor is preset in that system at a specific transmission ratio, which is to be provided to the continuously variable transmission upon switchover. Possible changes of the coordination of the transmission ratio with the switchover, for example wear-related changes, or a setting that is incorrect from the beginning, or the like, are not detected by that system.
It should be noted that the indicated state of the art is only an internal state of the art of the applicant and that, in that case, it reserves the right for seeking protection also for those embodiments.
The object of the invention is to produce a differently-configured method for controlling a continuously variable transmission, a differently-configured continuously variable transmission, as well as an electronic control device with which a method for controlling a continuously variable transmission can be carried out.
The object is attained by a method that has at least one of the features that are described in the following description or claims, or that are shown in the drawing figures.
The object is also attained by an electronic control device that has at least one of the features that are described in the following description or claims, or that are shown in the drawing figures, or that can carry out a method in accordance with the invention.
The object is also attained by a continuously variable transmission that has at least one of the features that are described in the following description or claims, or that are shown in the drawing figures.
In accordance with the invention, there is particularly provided a method for controlling a continuously variable transmission, wherein at least one switchover point or one switchover range of a multiple stage torque sensor is established or adapted. At that switchover point or in that switchover range, the torque sensor is switched over from a first stage of the torque sensor to a second stage of the torque sensor. In those different stages, with a given input load, in particular with a given torque at the input side, in particular on the engine side, the torque sensor produces different loads on the output side, in particular different forces that act on the disk set of a continuously variable transmission. The establishment and/or adaptation is undertaken in particular as a function of at least a first and/or at least a second operating parameter. It is particularly provided that by means of a first and by means of a second operating parameter, the switchover range or the switchover point is described or defined.